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김현수,권양수,이일신,정재학,김성일,Kim, Hyeon-Su,Kwon, Yang-Soo,Lee, Il-Shin,Chung, Jae-Hak,Kim, Seong-Il 한국음향학회 2009 韓國音響學會誌 Vol.28 No.3
수중 시역전 통신기법은 복잡한 수중채널환경에서 정합장 처리를 통해 수신단의 구조가 간단하면서 전송성능을 높이기 때문에 많은 연구가 진행되어 왔으나 디지털 시역전 통신을 하기 위한 전송변수에 대한 연구가 부족하다. 본 논문은 수중시역전 채널과 전송방식을 분석하여 시역전 통신이 공간 다이버서티 이득을 얻을 수 있음을 보였다. 그리고 디지털 시역전 전송 시 전송심볼간의 간섭을 회피하여 최적의 성능을 얻을 수 있는 통신변수인 심볼 구간, 프레임의 길이 및 전송 프로토콜에 대한 설계방법을 제안한다. 전산모의실험을 통해 제안된 설계변수를 이용한 시역전 통신에서의 전송심볼간 간섭효과를 보였다. 또한 보다 많은 트랜스듀서를 사용할수록 시역전 효과에 의해 부정합 신호경로의 개수와 크기가 줄어 ISI의 효과가 감소함을 보였다. The time reversal mirror (TRM) method for underwater communications has been developed to improve transmission performance with low complexity. However, digital communication parameters for TRM have not been researched deeply. This paper demonstrates that the TRM scheme obtains spatial diversity gain similar to multiple antennas, and proposes design methodologies of symbol interval, frame duration and transmission protocol for time reversal mirror transmission. Simulation results show that spatial diversity gain is achieved and the effect of ISI decreases as the number of transducer increases.
수중음향채널에서의 시역전 기법을 적용한 양방향 통신 방식의 용량 분석
김현수,권양수,유재호,정재학,김성일,Kim, Hyeon-Su,Kwon, Yang-Soo,Yoo, Jae-Ho,Chung, Jae-Hak,Kim, Seong-Il 한국음향학회 2009 韓國音響學會誌 Vol.28 No.6
본 논문에서는 원거리 수중음향 통신환경에서 중계노드가 사용가능한 센서노드 간의 데이터 교환을 위해 시역전 방법을 적용한 두 단계 양방향 수중 중계노드 통신 방식을 제안한다. 제안된 방법은 기존의 4 단계 중계절차를 2 단계로 줄이기 위해 시역전 기법을 이용한 양방향 통신방법을 적용하였으며 이를 통해 향상된 시스템 통신 용량을 얻는다. 또한 중계노드가 낮은 복잡도로 구현이 가능하기 때문에 효과적으로 전송 거리를 증가시킬 수 있다. 전산모의실험을 통해 제안된 방법이 기존의 방법보다 20 dB의 SNR에서 약 3.2 bps/Hz만큼 향상됨을 보였다. In this paper, we propose a bi-directional communication method applying time reversal technique in underwater acoustic channel in order to exchange data between sensor nodes with an available relay node. The proposed method reduces the conventional 4-step relaying procedure to 2-step and improves the system capacity. Moreover, it increases transmission range efficiently while the relay node can be implemented with low complexity. Simulation results demonstrate that the proposed scheme achieves 3.2 bps/Hz higher capacity than that of the conventional method at SNR 20 dB.
김현수,이영일,강봉균,송창길,전택기,Kim Hyeon Soo,Lee Yong Il,Kang Bong Kyoon,Song Chang Khil,Jun Taek Ki 한국관개배수위원회 2005 한국관개배수논문집 Vol.12 No.1
This study was carried out to obtain basic data for the agricultural water development project in Jeju-do. In this study, Jeju-do was divided into four regions considering the precipitation and soil characteristics. Water used for irrigation of the major
대한 정형외과 전공의 평가시험에서 족부-족관절 분야 문항 분석
김현수,김동희,신성진,강병률,Kim, Hyeon Soo,Kim, Dong Hee,Shin, Sung Jin,Kang, Byoung Youl 대한족부족관절학회 2017 대한족부족관절학회지 Vol.21 No.3
Purpose: The purpose of this study was to evaluate the questions pertaining to the foot and ankle on the Korean Orthopedic In-Training Examination (KOITE) between 2012 and 2016. Materials and Methods: Questions regarding the foot and ankle on KOITE during the five-year period (2012~2016) were analyzed. Number of foot and ankle questions, topics, taxonomic classification, imaging modalities, and cited references related to each question were analyzed. Results: The average number of foot and ankle questions was 35, accounting for 7.0% (35/500) of all KOITE questions. All questions were categorized into three topic areas: disease (51.4%, 18/35), trauma (31.4%, 11/35), and basics (17.1%, 6/35). Taxonomy 3 (decision-making type questions) was the most common (42.9%, 15/35). References that are commonly used for each question were Campbell's Operative Orthopedics (100%, 35/35) and the textbook of The Korean Orthopaedic Association (74.3%, 26/35). Conclusion: This analysis can be valuable to not only orthopaedic surgery residents to improve their knowledge of orthopedics, but also to instructors for optimizing their education programs.
김현수,진태호,동진근,Kim Hyeon-Soo,Jin Tai-Ho,Dong Jin-Keun 대한치과보철학회 1993 대한치과보철학회지 Vol.31 No.4
This study was designed to help to be given esthetics in construction of denture and prosthodontic rehabilitation of anterior tooth region. The author took the facial straight photograph of 100 old aged people(male 50, female 50) above 55 years of age, who have natural teeth in anterior tooth region, in a resting and a smiling position. And the author measured and analyzed the lip shape, the relation between the lip and the teeth and the change of lip length and height when they were smiling. The results of this study were as follows : 1. In the shape of the upper lip, when the upper lip curved downward, it was 53%, straight was 28% and curved upward was 9%. 2. In the relation between the upper lip and the teeth, average smile was 53% , high smile was 26% and low smile was 21%. 3. In the parallel relation between the lower lip and maxillary anterior incisal curvature, the group of straight was 54%, the group of parallel was 40% and the group of reverse was 6%. 4. In the relationship between maxillary anterior incisor and lower lip, the group of not-touching was 92%, the group of touching was 5% and the group of the maxillary anterior incisor were slightly covered by the lower lip was 3%. 5. In the teeth displayed in a smile, displayed to second premolar was 50%, displayed to first molar was 34%, displayed to first premolar was 12%, and displayed to canine and second molar were 2%. 6. At smiling, the width of the mouth was 0.94 times of the interpupillary distance and 0.45 times of the full face width. 7. At smiling, the length of the upper lip was 0.73 times and lower lip was 0.98 times of the length in a resting postion and the width of the mouth corner was 1.19 times of the resting position.